Appointed a painter of the Navy and the Colonies, Gaston Roullet participated in the military campaigns of Tonkin in 1885 and 1886 with the artistic mission given by the State to execute drawings. He was the only painter on the spot and produced about 70 watercolors and paintings on Tonkin during this period. His works - for the most part - were sold at an exhibition presented in 1886 and accompanied by a small autobiographical booklet called "An Artist in Tonkin and Annam".